The present invention relates to an audio input apparatus, a communication apparatus and a condition notification method.
An audio input apparatus that is a typical example of transceivers for commercial use is often used in an environment of much noise, such as a factory and a construction site. There is thus a demand for communication with clear voice sounds even in such a noisy environment by suppressing noise components included in a speech signal obtained through a microphone.
In order to meet the demand, there is a known audio input apparatus having an active noise-cancellation function using a main microphone for mainly picking up voice sounds and a sub-microphone for mainly picking up the surrounding noise.
In order to enhance the active noise-cancellation function in such a known audio input apparatus, it is preferable that a main microphone is oriented towards the user's mouth with an appropriate distance. In the case of a headset microphone (a close-talking microphone), a comparatively constant positional relationship is kept between the microphone and the user's mouth. On the other hand, in the case of a handset microphone, the positional relationship between a microphone held by a user and the user's mouth changes depending on how the user is using the handset microphone.
Moreover, it may happen that a handset microphone is used in a bad input condition of voice sounds for use in noise cancellation when it is held on the user's shoulder, a user talks into the microphone at a fairly long distance, etc. When a handset microphone is used in such a manner, it may happen that more voice sounds are picked by a sub-microphone than by a main microphone, which cancel a speech signal obtained through the main microphone, with the noise-cancellation function, resulting in transmission of unclear voice sounds.